A magnetic level gauge consists of a pressure tight chamber containing a float with a magnet inside. A visual indicator assembly is attached to the outside of the chamber, consisting of a series of flags or flippers rotatable 180 degrees. Each flipper contains a magnet which interacts with the float magnet to rotate 180 degrees as the float moves past the flipper in the chamber. The flipper rotates in one direction as the float moves past the flipper in a vertical direction, and back to its original position as the float moves in the opposite direction. The flippers each have contrasting colors on opposite sides, so they create a solid visual bar of color, one color below the current location of the float and the other color above the current location of the float.
The chamber is connected to a liquid process. The float has sufficient buoyancy to ride on the surface of the liquid as it moves up and down. The interaction between the float magnet and the flipper magnets, rotating the flippers as the float moves past as previously described, allows an external visual indication of the level of process liquid inside the chamber without exposing that liquid to the outside atmosphere or requiring direct visual sight of the process liquid.